1. Field of the Invention
This invention relates to a battery pack signal routing system.
2. Disclosure of Related Art
A conventional battery pack includes one or more battery modules disposed within a case and connected together, as seen by reference to U.S. Pat. No. 5,639,571 to Waters et al. Waters et al. disclose that the battery pack may also include a tray disposed within the case to support and orient the battery modules. Even though the battery modules are connected together in a string, there remains the need to sense voltage levels at each battery module. Waters et al. disclose an electrical wiring harness that includes individual cables or lead wires that are routed to the terminals of each module to provide for power transfer and to perform voltage sensing and other operations. In conventional systems, the lead wires may be attached to the terminals by various means including threaded fasteners and ring terminals or by threading multiple wires through a terminal crimp. Due to the use of individual cables, lead wires and fasteners, a relatively large amount of assembly time is required to assemble conventional battery packs. Further, the large number of parts and heavy reliance on human assembly renders conventional battery packs subject to damage during assembly and, therefore, reduces reliability. These problems are magnified when fuses and resistors or other current limiting devices are included in the battery. The fuses must be electrically isolated from various wires. The resistors must be spliced into the wires and must also be electrically isolated.
Conventional battery packs must also be configured to distribute air between battery modules and throughout the battery itself. Waters et al. disclose a housing or case that is molded to create baffles or openings to control airflow within the battery, thereby increasing the complexity and cost of producing the battery case. Further, it is difficult to make adjustments to airflow within the battery pack because of the complexity of the mold design and the difficulty in modifying the pre-molded case and tray.
To overcome some of the above-identified problems, a battery has been proposed that includes a rigid, printed circuit board to which one or more battery modules may be electrically connected. The circuit board may be used to sense voltage levels of the battery modules, thereby reducing and/or eliminating the need for many lead wires and fasteners. Although the proposed battery represents an improvement relative to many conventional batteries, the proposed battery fails to account for the required distribution of air among the battery modules. As a result, the proposed battery continues to suffer from the above-identified design problems associated with controlling airflow in the battery.
There is thus a need for a battery pack that will minimize or eliminate one or more of the above-mentioned deficiencies.
The present invention provides an improved battery pack.
A battery pack in accordance with the present invention includes a case, a flexible printed circuit supported within the case, and a battery module electrically connected to the flexible printed circuit. The battery pack is characterized in that the flexible printed circuit includes a plurality of airflow openings extending therethrough. In a preferred embodiment, the airflow openings vary in size relative to their proximity to an air source in order to maintain a relatively uniform airflow throughout the battery pack.
One advantage of a battery pack in accordance with the present invention is the use of a flexible printed circuit to perform voltage sensing, temperature sensing, current limiting, and other functions within the battery pack. The use of a flexible printed circuit reduces and/or eliminates the need for many individual cables, lead wires, and fasteners. As a result, the inventive battery pack requires less assembly time as compared to most conventional battery packs and is more reliable.
Another advantage of a battery pack in accordance with the present invention is that the flexible printed circuit may be used to control airflow within the battery pack. By using the flexible printed circuit to control airflow, the complexity and cost of the case and/or tray are significantly reduced. Further, adjustments to airflow within the battery pack may be made more easily than in conventional configurations.
A battery pack in accordance with the present invention may also include a buss interface to connect two or more battery modules within the battery pack. In one embodiment of the present invention, the buss interface includes a buss blade extending into the flexible printed circuit. In a second embodiment of the present invention, the buss interface comprises a substantially S-shaped conductive member operative as a female-type connector configured to engage the male-type terminals of two battery modules. The terminals of the two battery modules extend through the conductive member and into the flexible printed circuit. Each of the disclosed buss interfaces provides a compact and efficient means for establishing module to module power connections while allowing the flexible printed circuit to sense voltage levels within the battery pack (i.e., at each module-to-module connection).
These and other advantages of this invention will become apparent to one skilled in the art from the following detailed description and the accompanying drawings illustrating features of this invention by way of example.